base patch to implement 'jump labeling'. Based on a new 'asm goto' inlineassembly gcc mechanism, we can now branch to labels from an 'asm goto'statment. This allows us to create a 'no-op' fastpath, which can subsequentlybe patched with a jump to the slowpath code. This is useful for code whichmight be rarely used, but which we'd like to be able to call, if needed.Tracepoints are the current usecase that these are being implemented for.